239 research outputs found
Cosmic Electroweak Strings
We examine the Standard Model field configurations near cosmic strings in a
particular class of models. This class is defined by the condition that the
generator of the flux in the string, , commutes with the Standard Model
Lie algebra. We find that if the Standard Model Higgs carries a charge
under , cosmic string solutions have Z-flux , where is any integer and is the flux of the gauge field associated with . Only the
configuration with the smallest value of is stable,
however. We argue that the instabilities found at higher are just
associated with paths in configuration space reducing by
one unit. This contradicts recent claims that the instabilities in such models
represent the spontaneous generation of current along the string. We also show
that the stable strings have no Standard Model fermion zero modes: therefore
there is no possibility of supercurrents carried by Standard Model particles in
this class of models.Comment: Latex, 13 pages, 2 uuencoded figure
Mineralocorticoid Deficiency and Treatment in Congenital Adrenal Hyperplasia
Approximately 75%–80% of patients with Congenital Adrenal Hyperplasia (CAH) fail to synthesize sufficient mineralocorticoids to maintain salt and water balance. In most instances genotype can predict mineralocorticoid deficiency in CAH. Early recognition and replacement with 9α-fludrocortisone and salt supplements will prevent development of potentially lethal salt losing crises. In infancy a relative state of aldosterone resistance exists and replacement dose of 9α-fludrocortisone based on body surface area is higher during infancy compared to childhood and adults. Salt supplementation is generally not required after weaning is started. Regular monitoring of blood pressure and measurements of plasma electrolytes and renin are required to prevent complications of under or over dosage
Twisted Superconducting Semilocal Strings
A new class of twisted, current carrying, stationary, straight string
solutions having finite energy per unit length is constructed numerically in an
extended Abelian Higgs model with global SU(2) symmetry. The new solutions
correspond to deformations of the embedded Abrikosov-Nielsen-Olesen (ANO)
vortices by a twist -- a relative coordinate dependent phase between the two
Higgs fields. The twist induces a global current flowing through the string,
and the deformed solutions bifurcate with the ANO vortices in the limit of
vanishing current. For each value of the winding number (determining
the magnetic flux through the plane orthogonal to the string) there are
distinct, two-parametric families of solutions. One of the continuously varying
parameters is the twist, or the corresponding current, the other one can be
chosen to be the momentum of the string. For fixed values of the momentum and
twist, the distinct solutions have different energies and can be viewed as
a lowest energy ``fundamental'' string and its ``excitations''
characterized by different values of their ``polarization''. The latter is
defined as the ratio of the angular momentum of the vortex and its momentum. In
their rest frame the twisted vortices have lower energy than the embedded ANO
vortices and could be of considerable importance in various physical systems
(from condensed matter to cosmic strings).Comment: 39 pages, 20 figure
Transport of flexible chiral objects in a uniform shear flow
The transport of slightly deformable chiral objects in a uniform shear flow
is investigated. Depending on the equilibrium configuration one finds up to
four different asymptotic states that can be distinguished by a lateral drift
velocity of their center of mass, a rotational motion about the center of mass
and deformations of the object. These deformations influence the magnitudes of
the principal axes of the second moment tensor of the considered object and
also modify a scalar index characterizing its chirality. Moreover, the
deformations induced by the shear flow are essential for the phenomenon of
dynamical symmetry breaking: Objects that are achiral under equilibrium
conditions may dynamically acquire chirality and consequently experience a
drift in the lateral direction.Comment: 25 pages, 16 figure
Repetitive Stimulation of the Pituitary with Growth-Hormone-Releasing Hormone Alters the Proportion of 22 and 20 Kilodalton Human-Growth Hormone Released
Background/Aims. 20 Kilodalton-hGH (20 K-hGH) is the second most abundant pituitary GH variant after 22 K-hGH. In the steady state the proportion of 20 : 22 K-hGH appears constant; does this proportion change with repetitive somatotroph stimulation? Methods. Forty adult males were randomised to receive a GHRH(1–29)NH2 bolus (0.5 μg/kg (n = 20) or 1.0 μg/kg (n = 20)), preceded or followed by a saline bolus, 1 week apart. Four to six weeks later, 10 subjects received 0.5 μg/kg GHRH(1–29)NH2 at 0, 60, 120, and 180 minutes. Clearance rate of 22 and 20 K-hGH was measured in 10 subjects. Results. Total amount/proportion of 22 K-hGH/20 K-hGH secreted was similar for both GHRH(1–29)NH2 doses. Repetitive stimulation reduced the amount of 22 K-hGH released whereas the amount of 20 K-hGH did not change significantly leading to an increase in the proportion of 20 K-hGH (P = .05). Half-life of 20 and 22 K-hGH were not significantly different (P = .55). Conclusions. Repetitive stimulation of the somatotroph may alter the proportion of GH variant released
The no-defect conjecture in cosmic crystallography
The topology of space is usually assumed simply connected, but could be
multi-connected. We review in the latter case the possibility that topological
defects arising at high energy phase transitions might still be present and
find that either they are very unlikely to form at all, or space is effectively
simply connected on scales up to the horizon size.Comment: LaTeX-REVTeX, 5 pages and 2 figures uuencoded, submitted to Phys.
Rev. Let
A systematic review of maternal smoking during pregnancy and fetal measurements with meta-analysis
Funding: The study was supported by the European Cooperation in Science and Technology, who provided funds for publication. KMG is supported by the National Institute for Health Research through the NIHR Southampton Biomedical Research Centre and by the European Union's Seventh Framework Programme (FP7/2007-2013), projects Early Nutrition and ODIN under grant agreement numbers 289346 and 613977.Peer reviewedPublisher PD
Prenatal androgen exposure alters girls' responses to information indicating gender-appropriate behaviour.
Individual variability in human gender-related behaviour is influenced by many factors, including androgen exposure prenatally, as well as self-socialization and socialization by others postnatally. Many studies have looked at these types of influences in isolation, but little is known about how they work together. Here, we report that girls exposed to high concentrations of androgens prenatally, because they have the genetic condition congenital adrenal hyperplasia, show changes in processes related to self-socialization of gender-related behaviour. Specifically, they are less responsive than other girls to information that particular objects are for girls and they show reduced imitation of female models choosing particular objects. These findings suggest that prenatal androgen exposure may influence subsequent gender-related behaviours, including object (toy) choices, in part by changing processes involved in the self-socialization of gendered behaviour, rather than only by inducing permanent changes in the brain during early development. In addition, the findings suggest that some of the behavioural effects of prenatal androgen exposure might be subject to alteration by postnatal socialization processes. The findings also suggest a previously unknown influence of early androgen exposure on later processes involved in self-socialization of gender-related behaviour, and thus expand understanding of the developmental systems regulating human gender development.This is the author accepted manuscript. The final version is available from Royal Society Publishing via http://dx.doi.org/10.1098/rstb.2015.012
Effect of oxandrolone and timing of pubertal induction on final height in Turner’s syndrome: randomised, double blind, placebo controlled trial
Objective To examine the effect of oxandrolone and the timing of pubertal induction on final height in girls with Turner’s syndrome receiving a standard dose of growth hormone
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